Geoege amborn



(No Model.) I

G. AMBORN, JR, 8513. D. CHAPLIN.

GALIPBRS- No. 277,973. Patented May 22,1883.

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UNIT D- STATES PATENT ()EEicE,

GEoEGE AMBORN, JR, AND EDWIN D. OHAPLIN, oEPAwTUcKET, n. I.

CIALIPERS.

SPECIFICATION forming part of Letters Patent No. 277,973, dated May 22, 1883.

Application filed March 1, 1863. (No model.)

To all whom it may concern Be it knownthat we, GEORGE AMBoRN, J r., and EDWIN 1). GHAPLIN, of Pawtucket, in the county of Providence, State of Rhode Island, have invented a certain new and useful Improvement in Calipers, of which the following is a description sufliciently full, clear, and exact to enable any person skilled in the art or science to which said invention appertains to make and use the same, reference being had to the accompanying drawings, forming a part of this specification, in which- Figure 1 is an isometrical perspective view of a pair of calipers embodying our improvement Fig. 2, a vertical longitudinal section of the screw nuts and washer removed, but connected; and Fig. 3, a like view, showing the same parts removed and disconnected.

Like letters of reference indicate correspondelaborate description unnecessary.

In the drawings, A represents the body or spring-bow,.B O the arms, and D the connecting-rod or screw, of the calipers. The rod is jointed to the arm B and passes through a slot in the arm 0 in the usual manner, but is slightly longer than is. necessary in ordinary calipers, and preferably provided with a somewhat finer screw-thread. Disposed on the rod there is a nut, E, having the rosette f and elongated body G, the body being exteriorly threaded nearly its entire length with threads coarser or of a greater pitch than those on the rod D.. A nut, H, interiorly threaded to fit the body G, and provided with the rosette m, is disposed on the nut E, the body a of the nut H being preferably shorter than that of the go nut E. An ordinary V-shaped washer, J, is

placed beneath the nut H on the rod D, being prevented from turning with said nut by acorresponding V-shaped groove, (Z, in the arm 0, into which the washer fits.

In the use of ourimprovement for adjusting the calipers they are taken in the left hand, with the bow or body toward the wrist, the rosette m of the nut H being grasped firmly. between the thumb and forefinger to prevent it from turning. The rosettef of the nut E is then grasped between the thumb and forefinger ot' the other hand and turned to the rightor left, to open or close the calipers, as the case may be. For instance, to adjust the calipers with an opening movement of the arms, the nut H is grasped and held as stated, and the nut E turned in or to the right, this nut act ing through the nut H on the washer J, and tending to close the arms of the calipers; but at the same time the body G ot'the nut E, being turned into the nut H, will tend to withdraw said last-named nut from the washer or cause it to traverse toward the outer end of the rod D, and at a greater speed than the nut E is traversing in the opposite direction, or at a speed just in proportion to the difference between the pitch of the threads on the rod and the pitch of the threads on the body G, thereby producing a compound or differential m we ment which will enable the calipers to head-- justed with the greatest degree of accuracy. To adjust them with a closing movement of the arms it will be obvious that the nut E should be turned back, or-to the left, instead of the right. i

It will also be obvious thatour improvement is equally adapted to dividers, protractors, and all similar tools or implements where great accuracy of adjustment is. desirable also, that the washer may be omitted without departing from the spirit of our invention.

When not being adjusted, or when it is desired to open or close the arms of the calipers rapidly, the nut H is left free to turn with the nut E, which it does on account of the friction 5 between the two nuts being greater than that between the nut H and washer J.

Having thus explained our invention, what we claim is- 1 1. The improved calipers described, the same consisting of the spring-bodyA, having the I ing adapted to be moved toward or from each arms B 0, provided with the rod D, nuts E H, other at difierential speeds, substantially as [O and washer J, constructed, combined, and arand for the'purpose set forth.

ranged to operate substantially as specified. GEORGE AMBORN, JR. 5 2. In an adjusting device for calipers and EDWIN D. OHAPLIN.

similar implements, an exteriorly and inte- Witnesses:

riorly threaded nut carrying an auxiliary nut I EDWIN A. GROUT, and mounted on a threaded rod, the nuts be- SYLVANUS D. HORTON. 

